1. Field of the Invention
The present invention relates to a ceramic capacitor. Specifically, the present invention relates to a multilayer ceramic capacitor that includes a multilayer body including a stack of inner electrodes and dielectric layers, and outer electrodes disposed on the surface of the multilayer body so as to be connected to the inner electrodes.
2. Description of the Related Art
In recent years, multilayer ceramic capacitors including a multilayer body constituted by a stack of inner electrodes and dielectric layers, and outer electrodes disposed on the surface of the multilayer body so as to be connected to the inner electrodes have been widely used in various applications. One example of such a multilayer ceramic capacitor is a multilayer ceramic capacitor (multilayer ceramic electronic component) disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2010-129621.
As shown in FIG. 5, this multilayer ceramic capacitor (multilayer ceramic capacitor 101) includes a multilayer body (ceramic multilayer body) 105 constituted by a stack of dielectric layers (ceramic layers) 102 and inner electrodes 103 and 104 arranged with the dielectric layers 102 therebetween, and a pair of outer electrodes 112 and 113 disposed on opposite-end surfaces 108 and 109 of the multilayer body 105, respectively, so as to be in electrical communication with the inner electrodes 103 and 104, respectively.
Each of the outer electrodes 112 and 113 of the multilayer ceramic capacitor 101 is formed in the following manner. A brazing material containing Ti is applied to at least a part of the surface on which the outer electrode 112 or 113 is to be formed, which includes main faces 106 and 107 of the multilayer body 105, and the brazing material is baked, such that a metal layer 119 containing Ti is formed. Then, platings 114, 115, and 116 are formed so as to cover the metal layer 119, and an interdiffusion layer 120 is created between the metal layer 119 and the plating (Cu plating) 114 as shown in FIG. 6 (enlarged view of area B of FIG. 5).
Japanese Unexamined Patent Application Publication No. 2010-129621 states that the above-described structure makes it possible to provide a multilayer ceramic capacitor (multilayer ceramic electronic component) 101 that has outer electrodes 112 and 113 strongly bonded to the multilayer body 105 and that is highly resistant to moisture.
However, the multilayer ceramic capacitor (multilayer ceramic electronic component) 101, which has the above-described structure, has a problem in that, although the multilayer ceramic capacitor 101 has the interdiffusion layer 120 between the metal layer 119 and the plating 114, the multilayer ceramic capacitor 101 does not always have a sufficient reliability in moisture resistance, depending on the degree of interdiffusion of a Ag—Cu—Ti alloy (metal layer 119) and Cu (plating 114).
The multilayer ceramic capacitor 101 further has the following problem. Assume that one of opposite ends of the metal layer 119 in the direction in which each of the inner electrodes 103 and 104 extends to an end surface of the multilayer body 105 (i.e., the end which is closer to the end surface 108 or 109 of the multilayer body 105) is referred to as the end-face-side end and the other end of the metal layer 119 (i.e., the end which is closer to the center in the direction of the length of the multilayer body 105) is referred to as the center-side end. Since the plating 114 entirely covers the metal layer 119, when the interdiffusion of metals occurs at the center-side end of the metal layer 119, thermo-mechanical strength (flexural strength) decreases.